Charge former



's pt- 1943. i G. WEICHE I 2,330,650

CHARGE FORMER Filedjune 15. 1940 r jnvenfor Geo N? \Jmke Patented Sept.28 1943 Georg Weiche, Berlin-Reinickendorf, Germany;

vested in the Alien Property Custodian Application June 15, 1940, SerialNo. 340,741

' In Germany May 27, 1939 3 Claims. (Cl. 261-50) This invention relatesto a fuel regulator for internal combustion engines and moreparticularly to a fuel regulating device for aircraft engines operatingwith fuel injection.

Devices adapted to automatically regulate the fuel injection and thefuel-air ratio are known. The present invention, however, is. concernedwith a device allowing the injection pressure of.

the fuel to be adjusted at will by the pilot, whereupon the fuel-airratio is automatically regulated in dependence on the selected fuelinjection pressure.

According to a known construction an instrument measuring the quantityof air fed ina unit of time is arranged in the air intake of the engine.This measuring instrument serves for controlling the amount of fuel tobe injected and it measures the weight of'the air fed in a unit of time.If a venturi is used as the measuring instrument, then the volume of theair fed in a unit of time is a quadratic function of the effectivepressure prevailing between the air pressure in front of the venturi andthe pressure at the throat of the venturi where the rate of flow islargest. By additionally influencing the device for measuring the volumeof air in dependence on the condition of the air passing through the,venturi, the weight of' the air fed in a unit of time is determined.The amount of fuel to be injected is proportioned and regulated inaccordance with the weight of the air thus determined.

The known construction mentioned above is,

based upon the knowledge that with a constant density of the air and fora predetermined fuelair ratio thefefiective pressure of the venturi isproportional to the pressure difference prevailing at and behind thefuel 'nozzle. This knowlto the weight of the air passing through theventuri for influencing a valve controlling the fuel flow. This deviceis subjected, on the one hand, to the action of the difference inpressure edge is utilized by providing a device responsive prevailing inthe venturi, and on the other hand,

. to the. action of the difference in pressure prevailing at the fuelinjecting or spraying nozzle.

'A control slide connected to this air/ pressure responsive device isrelieved of the pijessure of the fuel pump and is used for controllingthe weight of the air fed in a unit of time in accordance with themomentarily prevailing requirementssuch as take ofi, cruising, fullload, idle running of the airplane. The corresponding alteration of theweight of the air fed in a unit of time is coordinated to this arbitraryalteration of the fuel pressure. This is obtained by the automaticregulation of the mixture of fuel:

and air. However, according to the present invention a device isprovided which prevents an increase of the pressure of the fuel above apredetermined highest pressure.

Besides the regulation of the number of revolutions, the ignition pointand so on, the fuel.

pressure is adjusted by way of a plurality of cams mounted, forinstance, upon a shaft actuated by the pilot's hand lever, whilesimultaneously the weight of the air fed in a unit of time is regulatedby a corresponding adjustment of the throttle valve provided in the airintake pipe by way of a leverage connected to the pilots hand lever. Aspecial piston control slide is provided for actuating a servo motorinfluencing the leverage connecting the air throttle valve with thepilots hand lever. This piston control slide is subjected, on the onehand, to the injec-,

tion pressure produced by the fuel pump and influenced by a cam that isarranged upon the hand lever actuated shaft, an elastic member beinginterposed between said cam and the piston control slide. The pistoncontrol slide, therefore, on the one hand, is influenced by way of thepilot's h: ind lever and, on the other hand, is subjected to the actionof the fuel pressure controlled by the automatically operatingregulating device. By adjusting the pilots hand lever the control slideis, by way of an elastic member, such as a spring, shifted from itsmiddle position until the servo piston has, by means of the throttlevalve, adjusted the admission of air in a unit of time in accordancewiththe selected fuel injection pressure. Simultaneously,

the air pressure responsive device adjusts the selected fuel injectionpressure so that the con trol slide is again'brought into itsmiddleposition and the servo piston comes to rest. If the attitude offlight and therewith the density of air arealtered, the control slideand the servo piston are influenced by way of the automatic regulatingdevice in order to change the position of the throttle valve in such amanner that always the same weight of air fed in aunit of time iscoordinated to the selected fuel injection pressure and thereby to adefinite amount of fuel fed'ina unit of time.

With the device according to the present invention the position of theoperating or control lever for certain kinds of loading, idle running,cruising, full load, overload, remain equal in all altitudes of flightand may-be marked by stationary notches. Another service improvement isobtained if the piston control slide simultaneously serves as-a safetyvalve. This arrangement is advantageous to prevent undesired increasesof pressure in the fuel injection pipe system which 4 occur for instanceif the load of the engine is suddenly reduced from full load to a lowerload.

Instead of the just described regulating device for an automaticregulation an automatically operating device also may be used forming'aunit with the fuel injection pressure selector according to the presentinvention, provided that this automatic regulating device controls thefuel in- Jection pressure in dependence on the weight of the air fed ina unit of time.

Other features of the present invention will be evident from thefollowing specification taken in connection with the accompanyingdrawing,

. This is effected by controlling the feeding pressure of fuel pump 28in dependence on they pres-. sure prevailing in space 29 and applied byway of pipes 29, 32 to pump 28 until equilibrium between control slide24and piston 22 is obtained.

wherein a construction according to the present invention isdiagrammatically shown by way of example.

The engine I, shown here for the sake of simplicity as a single cylinderengine, drives by way of gears 2 and 3 centrifugal fan 4 of thesupercharger 5. Venturi 6 is connected to supercharger 5. Venturi 6extends into air supply pipe I in which throttle valve 9 is pivoted atB. At the throat of venturi'fi 'where the rate of flow of air ishighest, tapping I is provided. A short distance in frontof venturl 5 afurther tapping H is provided in air supply pipe I at a point where theair drawn in by the supercharger'5 begins to be compressed. Thedifference of pressure between tappings II and I0 is the effectivepressure. Fuel injection nozzle I2 is arranged in box I1 subjected to.the condition of air prevail-- ing at tapping II is arranged in spaceI6. Barometric box I! is connected to regulating member I8 extendingthrough opening l9 into space 29 arranged above space I6. When movedunder the action ofbarometric box I 'l, regulating member 18 mayenlarge, reduce or completely close opening I9. Pipe 2I leads fromtapping I9 by wayof pipe I4 to space 20 to enable the air conditionprevailing in space I6 to be influenced, by way of barometric box I1 andthe regulating member I8 by the air condition prevailing at the tappingI9.

Piston 22 is arranged in casing I5 and preferably has a circular crosssection. The upper surface of piston 22 is influenced by the conditionof the air drawn off at II and conducted by way of pipe I6 into thespace above piston 22. The air pressure may additionally be influencedby way of pipe 2I and space 20, whereas the lower surface of piston 22is influenced by the pressure prevailing at tapping I0. As both surfacesof piston 22 are acted upon, a definite pressure always is applied tothe piston which pressure again is additionally influenced by way oftapping I3 and pipes 52, 53 with a view to correct the pres the spiralcasing of supercharger 5, and behind fuel nozzle I2 another tapping I3is provided near Then the amount of fuel supplied under the regulatedpressure flows from the pressure pipe of pump 28 through passage 26 andbore 21 into space 29' and pipe 29. From pipe 29 the fuel then flowsthrough the pressure reducing device 30 and pipe 3| tonozzle' I2 bymeans of which the fuel is injected into supercharger 5. By way of pipe32 this pressure is conducted to space 34. Control slide 34, shiftablyarranged in casing 33, influences in a well known manner servo piston36, displaceably mounted in cylinder 35 by the admission of oil underpressure into the space below and above piston 36. The pipes supplyingand discharging the oil under pressure are sche-- matically indicated inthe drawing by arrows. Two stops 3! and 38 limit the stroke of piston36.

Piston rod 39 is linked to connecting lever 40 'which in turn ispivotally connected to rod 4I.

Rod 4I-is connected to lever 42 for adjusting the throttle valve 9. Rod43 is connected to connecting lever 40 and rod 43 in turn is linked toone arm 44 of bell crank lever 44, 46 mounted upon shaft 45. 'The otherarm 46 of bell crank lever 44, 4B participates in the movements of thepilot's hand lever not shown in the drawing.

Cam 5| mounted upon shaft influences valve 30' of the pressure reducingdevice 30. Cam 47! also mounted upon shaft 45 forces by way of roller 48biassed spring guided in sleeve 49 against control slide piston 34.Connecting pipe system 52, 53, 54, the branch 53 of which discharges atI3 near nozzle I2 into supercharger 5 transmits the pressure fluctuationoccurring at I3 upon control slide piston 34. 4 I The device of theinvention operates as folows:

If the pilot actuates the pilot's control lever, bell crank lever 44, 46mounted upon shaft 45 1s swung for instance in a clockwise direction.This causes a clockwise rotation of cam 41. Cam 4! now acts by way ofroller 48 and sleeve 49 upon tensioned spring 50 bearing against thelower surface of control slide piston 34. The air pressure prevailing atthe fuel injection point in supercharger casing 5 and supplied by way ofthe pipe 54 also acts on the lower surface of control slide piston 34.This air pressure is opposed by the fuel injection pressure applied tothe head of piston 34 by way of the pipes 29, 32. Control slide piston34 now leaves its middle or inoperative position shown in the drawinguntil the two forces, viz. pressure prevailing in space 34' and pressureexercised by spring 50 as well as the pressure at fuel injection pointI3 supplied by way of pipes 53 and 54 are in equilibrium. If thepressure exercised by spring 50 and pipe 54 is preponderating, thenthemiddle portion of piston 34 formed as control slide for actuating servopiston 36 allows the oil under pressure admitted by way of a supply pipeto enter above servo piston 36 and to move it downwardly. Throttle valve9 then rotates towards its opening direction until the larger effectivepressure corresponding to the fuel injection pressure is adjusted andthe effective pressure has balanced the selectedfuel injection pressurein the fuel regulator. Then piston 34 again occupies its middle orinoperative position and the movement of throttle valve 9 stops.

A change in the attitude of flight and therein venturi 6 resulting fromfully opened throttle valve 9 and thereby-the coordinated lower fuelinjection pressure may be adjusted only as long as the air densitycoordinated to the desired fuel injection pressure is sufiiciently lowwhich may be achieved by a downward movement of the aircraft to a loweraltitude of flight. Only then will the fuel injection pressure beconstant, a corresponding regulation of throttle valve by means ofautomatically regulating device l52l b'eing effected. The variousadjustments of the pilot's control lever, therefore, may remain the sameinall altitudes, whereby definite kinds of load, such as idle runningeconomic flight, full load and overload, may be adjusted by'engaging thepilots control lever in stationary notches. To prevent undesiredincreases of pressure in fuel injection pipe 3!, the piston 3tsimultaneously is formed as a safety valveso that, if a fuel injectionpressure higher than the adjusted fuel pressure occurs, piston 34 isovercontrolled and'opens pipe 51, whereby the fuel present in space 34'directly is returned, by way of pipe 51, into the suction pipe of fuelpump 28. Accordingly, the pressure directly drops to the desired degreeuntil throttle valve 9 is adjusted. Also if the engine is adjusted foridle running, the overpressure, that suddenly occurs in space 34 forcescontrol piston slide 3d downwards. Therefore, the fuel flows by way ofpipe 51 back into the suction pipe of fuel pump 28. Thus an undue supplyof fuel causing too rich a mixture is prevented.

What I claim is: 1. In an internal combustion engine, the combination ofan air admission pipe having a throttle pivotally mounted therein, asource of fuel supply under substantially constant pressure, said sourceof fuel supply having a pressure side and a suction side, apparatus forautomatically adjusting the air-fuel ratio including a device responsiveto the weight of the air passing through said air admission pipe forselecting at will the fuel injection pressure including a pilot's lever,a control device adapted to be controlled by said pilot's lever, acasing, a control slide slidably mounted in said casing and adapted tobe actuated by said control device and influenced by said deviceresponsive to the weight of the air and by the pressure of said sourceof fuel supply as controlled by said-apparatus; a spring biased sleevefor keeping said control slide in equilibrium, an instrumentality forcontrolling said throttle valve by said control slide, said controlslide altering the position of said throttle valve until the air fed ina unit of time has a predetermined ratio with respect to the selectedfuel pressure and until said control slide is simultaneously returnedinto its inoperative position a fuel supply by-pass through said casing,and a valve for said by-pass operable bythe control slide in furthermaintaining a fuel-air-flow ratio.

2. Adevice as claimed in claim 1 wherein a relief pipe is providedconnecting said casing with the suction side of said source of fuelsupply so that when the pressure of said fuel supp y source ascontrolled by said apparatus exceeds a predetermined amount said controlslide opens said relief pipe. whereby over control of said fuelinjection pressure selecting mechanism is prevented.

3. A device as claimed in claim 1 wherein said instrumentality forcontrolling said throttle valve by said control slide includes a servomotor controlled by said control slide for actuating said throttlevalve.

GEORG WEICHE.

